EAGER: Exploring Links between Iron and Phosphorus Nutrition of Antarctic Marine Phytoplankton

浮游植物是微小的单细胞植物，生长在阳光照射的海洋表面。在南极洲周围的南大洋，浮游植物生活在次优条件下，因为海水中的铁含量不足以生长。此外，南大洋浮游植物的化学组成与其他海洋区域不同，磷的比例高于其他元素，这一特点最终影响了营养物在整个海洋的分布。研究人员推测，南大洋浮游植物的高磷成分是由它们的低铁含量引起的。具体来说，他们假设浮游植物合成了一种富磷分子植酸，以帮助在指定的细胞区室（如液泡）中储存铁。最近的观察表明，一些浮游植物可以吸收植酸，这表明它可能是由某些物种产生的。植酸在土壤中普遍存在，它有助于植物根部对铁的吸收，同样也可以帮助南大洋的浮游植物通过细胞膜获得铁。该项目有利于美国国家科学基金会的目标，即提高对南大洋和全球海洋之间相互作用的理解，通过关注南极特有的浮游植物物种，扩大对南极生物群和相关过程的基础知识。作为该项目的一部分，康涅狄格大学文理学院海洋科学系将资助一名在科学领域代表性不足的研究生的招聘、搬迁和指导。该项目旨在确定南大洋浮游植物中不寻常的元素组成是否是贫血的结果。这项工作将询问肌醇六磷酸（植酸）是否有助于南极浮游植物获取和储存铁，从而导致细胞中磷相对于其他元素的比例升高。包括一名研究生在内的研究人员将用从南大洋分离出来的浮游植物菌株进行实验室培养实验。他们将在缺铁和补铁培养基中培养细胞，看看缺铁条件下它们的磷含量是否更高。他们将测试在磷充足的条件下生长的细胞是否能获得更多的铁，从而使它们在缺铁条件下比在缺磷条件下生长的细胞生长得更好。他们还将询问在缺铁条件下生长的细胞在植酸存在下是否能达到更快的生长速度。结果将为CRISPR突变体的设计提供信息，用于研究南极海洋浮游植物中磷和铁的共代谢。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Phytoplankton are microscopic single-celled plants that grow at the sun-lit surface of the ocean. In the Southern Ocean around Antarctica, phytoplankton live in sub-optimal conditions because the amount of iron in seawater is insufficient for growth. Moreover, the chemical composition of Southern Ocean phytoplankton is distinct from that in other ocean regions, with a higher proportion of phosphorus relative to other elements, a characteristic that ultimately influences the distribution of nutrients ocean-wide. The researchers hypothesize that the high phosphorus composition of phytoplankton in the Southern Ocean is caused by their low iron content. Specifically, they postulate that a phosphorus-rich molecule, phytic acid, is synthesized by phytoplankton in order to assist in the storage of iron in designated cellular compartments, such as vacuoles. Recent observations show that some phytoplankton can absorb phytic acid, suggesting that it may be produced by certain species. Phytic acid is pervasive in soils, wherein it aids absorption of iron via plant roots and could similarly help phytoplankton in the Southern Ocean acquire iron via the cell membranes. This project benefits the National Science Foundation's goals of improving understanding of interactions between the Southern Ocean and the global ocean, of expanding fundamental knowledge of Antarctic biota and associated processes by focusing on phytoplankton species unique to the Antarctic. As part of this project, the Department of Marine Sciences from the College of Liberal Arts and Sciences at the University of Connecticut will sponsor the recruitment, relocation and mentorship of a graduate student under-represented in the sciences.This project aims to determine whether the unusual elemental composition of phytoplankton at the Southern Ocean is a result of anemia. The work will query whether inositol hexakisphosphate (phytic acid) aids Antarctic phytoplankton acquire and store iron, resulting in an elevated fraction of cellular phosphorus relative to other elements. The researchers, including a graduate student, will conduct laboratory culture experiments with phytoplankton strains isolated from the Southern Ocean. They will grow cells in iron- deficient versus iron-replete media to see if their phosphorus content is higher in iron-deficient conditions. They will test whether cells grown with sufficient phosphorus acquire more iron, allowing them to grow better in iron-deficient conditions than cells deriving from phosphorus-poor conditions. They will also query whether cells grown in iron-deficient conditions achieve faster growth rates in the presence of phytic acid. Results will inform the design of CRISPR mutants with which to investigate phosphorus and iron co-metabolism in Antarctic marine phytoplankton.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.